BRPI0808974A2 - METHOD FOR INCREASING THE CLARIFICATION CHARACTERISTIC OF A MIXING REACTOR AND A MIXING REACTOR - Google Patents

Description

"METHOD FOR INCREASING CLARIFICATION CHARACTERISTICS IN A MIXING REACTOR AND THIS MIXING REACTOR"

Field of the Invention

The present invention relates to a mixing reactor for mixing liquid and a pulverulent solid, clarifying the solution that is formed and removing the clarified solution from the mixing reactor, the lower section of which comprises a fluidized bed. The invention also relates to a method for mixing the liquid and the pulverulent solid in a fluidized bed, for clarifying the solution that is formed and for removing the clarified solution from the mixing reactor.

Background of the Invention

Mixing reactors are generally cylindrical and have standard diameters. Typically, they are equipped with baffles attached to the reactor walls to remove a central vortex that sucks gas from the surface, which is considered hazardous. Solid / solution phase processes usually require mixing, which includes potent turbulence and proper circulation.

Feed into the mixing reactor typically occurs by feeding the solid and solution into the upper reaction space. Generally, it is desired that in a continuously operating reactor, both solids and solution should be removed more or less with the sludge density that occupies the reaction space. Thus, it is not desirable for the heavier or coarse particles to remain in the reactor. Thus, it is natural that the removal of the sludge stream can be advantageously installed on the reactor wall, occurring mainly as overflow. However, there are cases where it is desired to remove the solution which reacted with the solids from the reaction space in pure form, ie without solid particles. One such case is disclosed in U.S. Patent No. 3,954,452,

in which the cementation reaction of the cadmium solution and zinc powder is performed at the beginning of the fluidized bed. When the solution is fed into the lower section of the reaction zone, efficient mixing is obtained in the fluidized bed. The bottom of the reactor widens conically upwards, 10 being cylindrical in shape from that upward point. There are baffles on the bottom wall of the reactor, which together with the mixing element grinds any clumps that are generated. The upper part of the reactor also widens conically upwards. Thus, reactor 15 consists of three zones: the reaction zone, the rest zone and the clarification zone, where the reaction zone is the bottom of the reactor, the center forms the rest zone, and the upper section of the reaction zone. clarification zone. A mixing element for use in the mixture itself is not used herein.

In the method according to U.S. Patent No. 3,954,452, the solution of the fluidization zone rises by conical widening to the clarification zone, where the solution removal unit is arranged over the wall of the clarification zone. The process presented is the cementation of cadmium solution and zinc dust. In this cementation reaction, cadmium powder is formed, which is lighter due to its age pores and at the same time also thinner. One objective is to prevent solid particles formed as reaction product from leaving the reactor together with the solution. Another difficulty encountered in this case has also been the stickiness that occurs between the splinters, that is, agglomeration. Gradually, the agglomerates grow to such a degree that the movement in the fluidized bed deteriorates and finally is completely stopped. For this reason, a flocculant solution is fed into the fluidization zone to prevent agglomeration. Since in practice the prevention is not completely perfect, a mixing element for grinding the agglomerates is located in the lower section and correspondingly small baffles are located in the walls to absorb impact force and avoid vortices. .

The force intensity and height distance of the

The surface of the fluidized bed (Hmax) that upwardly directed discharges reach depends on the conditions of the fluidization zone. Thus, it is important that the current rises above the aforementioned height as evenly and at the lowest possible speed.

However, in practice, what happens is that solution flows as directly as possible and along the shortest route towards the removal unit, so that the flow field becomes a conically curved cone. This, in turn, means that the current velocity of the solution carrier of any possible particles increases, and there is no chance of the particles themselves being released from the flow.

The problem with the equipment described above is that the bed material that prevents the removal of solids must be suitably thick. However, as the reaction proceeds, the particle size of the solids in the bed decreases, whereby the amount of solids taken with the solution increases.

30

Objectives of the Invention

The object of the invention presented herein is to eliminate the drawbacks that arise in the techniques described above by the prior art. Therefore, a mixing reactor in which a fluidized bed consisting of a liquid and solids is formed is such that the amount of solids contained in the solution removed from the fluidized bed is as small as possible.

Summary of the Invention

The mixing reactor according to the present invention is designed for mixing a liquid and a solid together in a fluidized bed for clarifying the formed solution and removing the clarified solution from the reactor, which consists of three sections. The lower section is typically a cylindrical reaction zone within which the solution to be treated and the pulverulent solid are fed to form a fluidized bed. The upper part of the fluidized bed section or reaction zone is connected to a conically widening upward rest zone. Connected to the top of the rest zone is a cylindrical clarification zone having a diameter equal to the top of the rest zone. The lower section of the reaction zone is equipped with a feed unit and a discharge unit is located in the clarification zone below the liquid surface, where the discharge opening is disposed essentially at the central axis of the reactor. At least one guide element for directing the solution flow is positioned in the vicinity of the discharge opening to prevent the flow of solid particles with the solution.

According to one embodiment of the invention, the supply unit for the liquid to be fed is directed obliquely downwards.

According to one embodiment of the invention, the decanted solution discharge unit is directed obliquely downwardly and the solution directing element of the solution is an annular flow prevention plate which is positioned around the discharge opening.

The flow prevention plate may be flat or upwardly tapered. The outside diameter of the flow prevention plate preferably is 20-30% larger than the diameter of the reaction zone.

As the decanted solution discharge unit is directed obliquely downward, the guide element directing the solution flow in addition to the annular flow prevention plate preferably also includes a guide ring above the latter directed at the direction of the reactor center from the reactor wall. Typically, the guide ring extends into the reactor wall for a distance of the order of 10-30% of the diameter of the clarification zone.

According to another embodiment of the invention, the clarified solution discharge unit is directed upwards, and the solution flow guide element is an adjustment plate which is located below the discharge opening.

According to one embodiment of the invention, a choke ring directed inwardly from the reactor wall is located between the reaction zone and the rest zone. Preferably, a gap is left between the choke ring and the reactor wall.

According to one embodiment of the invention, the reaction zone is equipped with a mixer rotor made of a spiral tube.

The invention also relates to a method for mixing a liquid and a pulverulent solid into a fluidized bed for clarifying the forming solution and removing the clarified solution from a mixing reactor. A fluidized bed composed of liquid and solids is arranged at the bottom of the reactor, its reaction zone (I), a rest zone (II) above it, in which the cross section widens upwards, a clarification zone (III). ) above it, whose cross section is equal to that of the upper part of the rest zone (II). It is typical of the method that the upwardly rising cross-sectional area of the solution stream in the clarification zone (III) is required to be widened by at least one guide element before the solution is removed principally. through the discharge opening of the discharge unit located on the central axis of the reactor. As the cross-sectional area widens, the solution flow rate decelerates and, simultaneously, the flow is forced to form return swirls in the vicinity of the reactor wall, within which the solid particles carried along with the solution decant. Then they fall back into the fluidized bed.

According to one embodiment of the method according to the invention, the liquid to be treated is fed into the lower part of the reaction zone in an oblique downward direction.

According to one embodiment of the method according to the invention, the upwardly rising cross-sectional area of the solution stream is required to be widened by means of a substantially horizontal plate-like guide member located below the discharge unit.

According to another embodiment of the method according to the invention, the upwardly rising cross-sectional area of the solution flow is required to be widened by means of an annular guide element located around the discharge unit.

According to a third embodiment of the method according to the invention, the upwardly rising solution flow cross-sectional area is required to widen by means of an annular guide element located around and above the discharge unit.

When the upwardly rising solution flow cross-sectional area is required to widen by an annular guide element located around and above the discharge unit, it is preferable that the above guide element extends from annular wall of the reactor towards the interior by a distance of the order of 10% -3 0% of the diameter of the 10 clarification zone.

The solids content in the clarification zone of the upper reactor is preferably set to around zero. The formation and maintenance of a fluidized bed is obtained by the solution flow being fed into the lower section of the reactor, which meets the requirement.

According to one embodiment of the method according to the invention, a rotary mixing element suitable for such purpose is used in the fluidized bed reactor 20 in order to enhance mixing and solution flow balancing. The essential features of the invention will become apparent from the reading of the appended claims.

List of Drawings

The equipment according to the invention is described in more detail with reference to the accompanying drawings, in which:

Figure 1 shows a vertical section of a prior art mixing reactor with its flow fields;

Figure 2 shows a vertical section of a main design of a mixing reactor according to the invention; Figure 3 shows a vertical section of the mixing reactor according to Figure 2 in greater detail;

Figure 4 shows a vertical section of another mixing reactor according to the invention;

Figure 5 shows a vertical section of a modification of a mixing reactor according to the invention; and

Figure 6 shows a vertical section of another mixing reactor according to the invention.

Detailed Description of the Invention

The object of the method according to the invention is to obtain a flow field type in a mixing reactor that facilitates attempts to prevent the removal of solid particles from a fluidized bed disposed in the reaction zone in question. Thus, the objective is to form a clarified solution and prevent the reactor discharge of particles rising from the reaction zone with the solution stream, and finally return said particles back to the lower reactor section.

The method now developed according to the invention for obtaining a controlled and desired flow field in a mixing reactor is based on the effect of balancing the discharge flow of the reactor fluidization zone or reaction zone solution and particularly in the deceleration effect and also the flow control effect caused by the guide elements of the reactor clarification zone. The balancing effect of the fluidization zone can be further optimized with an appropriate mixing element.

Figure 1 shows a state of the art mixing reactor (1) in which a liquid and a solid are treated so that the powdery solid forms a fluidized bed and at the same time reacts with the fed liquid. inside the lower section (2) of the reactor. The bottom section (2) of the reactor conically widens upward and extends upwardly into the middle section.

(3) providing a cylindrical shape. The upper section

(4) the reactor also conically widens upwards. The solution, which is markedly free of solids, is removed from the upper section of the reactor via a discharge unit (5) located on its wall. Attention should be paid to increasing the contact surface in the reactor between the solid and the solution and the energy explosion of the solution stream itself. Therefore, a fluidization zone (6) with a high mud content is formed in the central section of the reactor. In addition, the reactor is provided with a propeller (7) and baffles (8) for grinding the agglomerates, which are used on the one hand to try to prevent agglomeration and on the other hand to crush the agglomerates which they form into individual solid particles. Agglomeration is also prevented by continuously feeding a flocculating agent into the solution.

It is known that under certain conditions mud jets (9) form on the upper surface of the fluidized bed in the mixing reactor, which are directed upwards and which are of the fluidized bed category in terms of mud density and particle size. . The height of the jets (Hmax) can be calculated theoretically. This means that all solid particle sizes approach this height. Another flow-related phenomenon that results in solid particles terminating in the solution discharge stream is the fact that the flow, in fact, usually helps the discharge opening as directly as possible. Thus, a stream 10 is formed towards the discharge unit 5 where the cross-sectional area of the stream is continuously reduced. This in turn means that the flow in the flow field increases at the same rate. If the fluidized bed surface is uniform, the settling rate and said flow rate may determine the particle size of the solid particles leaving the solution. However, the aforementioned jets which are thrown upwards are capable of elevating the particles to the Hmax height, even those of a higher settling speed, so that their flow rate is greater than on the bed surface. As a result, solid particles are always discharged from the bed in greater quantities. As it may be supposed, an expanded upper section is not a solution in itself, although this undoubtedly improves the situation. Increasing the height of the expanded top section naturally helps prevent the removal of solid particles.

The flow event and mixing reactor belonging to the method according to the invention is first illustrated in a simple embodiment shown in Figure 2. The mixing reactor comprises three zones: the reaction zone 20 (I), the resting zone (II) and the clarification zone (III).

The reaction zone (I) is mainly cylindrical, with a constant cross-sectional area. The lower section alone narrows conically downward. The solution to be treated (11) is fed into the mixing reactor (12) with a downwardly directed tube (13) within the lower section of the fluidization zone formed by the powdery solid and the solution. In this simple manner, a uniform upward flow is achieved. In many cases no harmful agglomerates are formed, so more simply no more grinding or grating mixers are needed, as are baffles. Under certain conditions, upwardly directed mud jets are formed from the surface of the fluidization layer in the resting zone (II). In this section, the solid particles that left the top of the fluidized bed with the solution but then separated from it return to the reaction zone.

The diameter (T3) of the reactor in the clarification zone (III) is 1.5 to 3.0 times the diameter (T1) of the partial reaction zone, preferably 2 to 2.5 times, after which the Average solution elevation rates fall to between 0.44 and 0.11 times the elevation rate that occurs in zone (I) and correspondingly to between 0.25 and 0.16 times in the preferred case.

In accordance with the invention, a plate-like guide element (A) is positioned in the middle of the clarification zone. The guide element forces the flow of the solution that rises from the center of the zone towards the sidewalls, so that the flow is retarded. Since the plate-like guide element is an annular flow prevention plate which is positioned around the discharge opening (C) of the discharge unit (B), its outside diameter is larger than the diameter (T1) of the discharge. reaction zone (I), preferably around 20 to 30%. It is typical of the method and apparatus according to the invention that the discharge unit for reactor solution removal is located in the upper section of the clarification zone, about its central axis (D), but below the liquid surface (E ). The solution is removed from the reactor through the discharge unit and the discharge unit typically is directed obliquely downward and over the sidewall or alternatively, mainly directly upwards. The tilting of the discharge unit does not cause any major effects at first because the solution does not contain a significant amount of solids that can settle to the bottom of the unit.

When the relative average speeds of the above solution are 100% in the reaction zone (I) and 22% in the clarification zone (III), then in reality they will be 100% in the reaction zone, 62%. intermediate stages of the clarification zone and 29% near the lower guide plate. This means that as the velocity drops to 30%, some of the particles that are carried together fall out of flux precisely because of the clarification velocity. In addition, when the solution in the upper section falls within a curved flow, the proportion of particles separating increases as a result of the cyclone effect. The scalable side vortices directed toward the edges of the central section return the separated particles to the reaction zone (I).

The fluidization bed itself in the reaction zone prevents the discharge of fine particles and reduces the spacing of particles that have risen to the bed surface along with the solution. The retention of solid particles in the bed can be optimized by the advantageous placement of the solution feed, for example by feeding the solution obliquely downwards as seen in Figure 2. In addition, a mixing element can be used in the fluidized bed. replacing the grid generally located below the fluidized bed. As already described above, at least one flow guide element directs the flow located in the clarification zone. A discharge flow 30 less than the particle clarification rate is obtained by extending the upper clarification zone and locating the discharge aperture symmetrically about the central axis of the clarification part. Enhanced flow stabilization and cyclonic vortex formation are achieved with at least one flow guide element in accordance with the present invention.

A mixing reactor according to figure 2 is illustrated in figure 3 in greater detail. The solution to be treated (11) is fed to the mixing reactor (12), which in practice is carried out through a tube (13), directed obliquely downward into the reaction zone in the lower reactor section. , that is, the fluidized bed section (14) (I). The powder to form the fluidized bed is fed, for example, into batches in a manner known per se. The goal is not to decrease the amount of dust that acts as a bed, but rather to react with the solution. The intention is also to obtain the upwardly increasing fluidization effect as uniform as possible between the powdery solid and the solution. As is well known, fluidization promotes the most effective friction and variability for the contact surfaces between particles and solution. In principle, the bottom section is designed based on the delay and fluidization level required by the reactions. Fluidization level means the void between solids and solution, ie the ratio of solution to total volume (ε), which is usually in the range of 0.5 <ε <0.9. Fluidization level coupled with particle size determines the behavior of the bed, in other words, for example, whether the fluidization level is calm or jet-like eruptions.

The fluidization bed (15) has the required number of flow baffles (16) located on the side walls of the reaction zone. Sometimes, in reactions, the agglomerates begin to form from solid particles and their bonding must be interrupted by a mechanical grinding mixing element (17), such as that illustrated in the reactor of Figure 1.

The solution leaving the reaction zone (14) to the resting zone (18) (H) includes a certain amount of solid particles, which are suitably fine in particle size, this amount being determined by the rate of elevation of the solution and particle clarification rate as well as the height of the aforementioned mud eruptions (19). In the preferred case, the solution flow is so uniform that its elevation velocity can be roughly calculated from the formula:

w = Q / A where:

w = average solution elevation speed [m / s], calculated over the entire cross-sectional area of the reaction zone;

Q = solution flow [m3 / s]; and

A = cross-sectional area of reaction zone [m2].

Normally, when calculated in this way, the solution reaches a sufficient velocity so that downwardly directed swirls (21), typical of eruptions, are formed around the upstream (20), i.e. formation of a cyclone effect. These swirls try to compress the upstream and thereby promote the conjoint transport of the particles with the solution. The situation is slightly improved by using the rest area with conical upward widening.

In order for solid particles in the clarification zone (22) (III), which have separated from the fluidized bed, to be returned to the bed, the clarification zone must be of sufficiently large diameter, and particularly in height, in the range. 1.5-2.0 times the diameter of said clarification zone. In particularly larger reactors this is not feasible and other means are required. In the method and equipment according to the present invention, this was solved by the simple use of guide elements. The discharge opening (24) of the reacted solution discharge unit (23) is symmetrically located over the reactor central axis, where a horizontal annular flow prevention plate (25) is fixed to the upper edge of the discharge unit. A guide ring (26) directed from the wall towards the center of the reactor is located some distance above the flow prevention plate. As a result of the flow prevention plate (25), the flow of the solution (20) rising from the center of the reactor is directed towards the edge of the clarification zone, so that, as the area of cross section grows, speed is reduced. The guide ring (26) means that the flow is diverted towards the center and over the discharge opening (24). Thanks to the inertial force that occurs at the curve near the wall, in the area between the guide elements 25 and 26, the particles deviate from the discharge stream towards the wall and move within the downwardly directed return swirl ( 21) near the wall and then return to the reaction zone (14).

When another flow guide element is positioned at the top of the clarification zone (22) (III) in accordance with the present invention, the guide ring (26) is arranged to be above the flow prevention plate (25). ). The guide ring is fixed to the wall so that an annular clearance is left between the flow prevention plate and the guide ring when viewed from above. The vertical distance between the guide elements is determined by the ratio of the clarification and reaction zone diameters. The width of the guide ring is 10% to 30% of the diameter of the clarification zone.

The flow prevention plate 25 may at first be flat in that there is no significant amount of solid particles in the flow. If there is reason to fear that solids will accumulate on top of plate 25, this plate should be modeled in a funnel shape. This is shown in Figure 4, where the shape of the lower clarification zone guide element 10 or flow prevention plate (27) is tapered so that its outer edge rises above the discharge opening. In this case, the shape of the guide element prevents the possible accumulation of solids at the top of the plate and in the solution.

The solution shown in figure 4 is somehow prepared for the coarse and possibly still heavy particles fed into the fluidizing bed of the reaction zone to become thinner and lighter when they react with the solution fed in. of the reactor. Excess fineness solids (mostly below 400 mesh or 37 μιη) cannot be completely prevented from rising with the flow of reactor solution even with the arrangement according to the invention. In this case, it is necessary to accept a small amount of solids in the discharge. This means that the flow prevention flat plate is replaced by a conical plate (27) which when attached to the discharge unit (23) forms a funnel. When necessary, the inclination of the discharge unit can be changed.

An alternative for stabilizing flow in fluidized bed 30 and improving separation of the clarification zone 22 is presented in the application of the mixing reactor according to figure 5. Immediately above the fluidization layer, i.e. between the reaction zone (14) and the rest zone (18), an inwardly directed ring choke control is provided from the reactor wall. However, a spacing (29) is left between the wall and the control, whereby the solids-containing solution that circulates downward in the clarification zone can settle in the fluidized bed. As the name suggests, throttling control obstructs the rising solution flow from the reaction zone (14) and thus intensifies the vortex phenomenon of the clarification zone (18), ie the separation of solids from the solution. due to centrifugal forces. By throttling control, the rising solution flow is focused even more intensely on the central axis, where the rising vortices near the wall are intensified and the cyclone separating effect of the flow particles is enhanced.

Sometimes the flow distribution of the solution along the entire cross-section of the reaction zone has to be intensified with an appropriate mixing element, especially when the underbed grid construction in the solid-gas fluidization procedure does not. can be adapted substantially for solid-gas fluidization. A mixer (30) is placed in the reaction zone (14) of a mixing reactor according to figure 5 which is supported on the same axis (31) as the milling mixer (17). The mixer 30 preferably is a rotor mixer made of spiral tubes. This type of mixer is also capable of spinning at high mud densities. The purpose of the mixer is to mix the fluidized bed and prevent it from becoming arched. The aim is also to spread the flow of the rising solution as evenly as possible across the entire cross section, that is, it may be called a "grid mixer" because its purpose is to act as a grid replacement in fluidized bed. When a mixer is used in the fluidized bed, the advantage is that a finer solid than the previous one may be required to remain in the bed and will not be removed as the solution flows.

In the embodiment shown in figure 5, a provision is made for the occurrence of large variations in capacity. In this case, for example, as the solution current becomes smaller, the fluidization state of the reaction zone may weaken and may even partially change within what is known as a fixed bed, after which, The movement of solid particles is reduced, weakening the shear stress required for the reactions. A spiral tube mixer enables not only improved liquid and solid distribution across the entire bed cross section, but also a variable amplitude mixing area in the reaction zone. If the mixer on the shaft is inserted from below, the upper section must be provided with a support centering ring.

In the embodiment of a mixing reactor shown in Figure 6, solid particles are prevented from traveling along with the solution in a slightly different path from previous resolutions. The solution is removed from the reactor (12) in the upwardly directed discharge unit (32), which, however, is disposed below the solution surface and specifically the central axis of the reactor. Thus, a flow symmetry is implemented, thanks to the funnel-like flow shown in Figure 1, which is reduced in cross-sectional area and is not generated here either. Instead, an enlargement flow field is deliberately generated, where the solution flow rate in the clarification zone 22 falls almost to the ideal average value.

A horizontal guide element (34), which in the simplest form is a circular adjusting shim, is established below the solution discharge opening (33). The shim acts as a guide plate, forcing the rising solution flow to expand laterally, and as a prevention plate, preventing the rising solution flow 5 from flowing straight into the discharge opening. The embodiment of a mixing reactor according to the present invention shown in figure 6 is probably the simplest. Of course, the adjusting shim may also be of a more adaptable flow shape, e.g. of conical structure. Of course, the wedge shown here, as well as the guide elements shown in the other figures, can be supported by the reactor wall as well as by the edge of the discharge opening.

In all cases, the height adjustment of the

surface occurs using normal technology.

Examples

Example 1

In the present example a comparison is made between the state of the art (A corresponds to Figure 1, but the clarification zone has increased height to the size of Figure 6) and the present invention (B corresponds to Figure 6). In both cases, the process reactor and the basic conditions are the same. Two different powder materials are used. In the reactor according to the present invention (B), the diameter of the circular adjusting shim is Φ = 85 mm. These 4 different cases are presented in the following Tables 30, where:

Al = a state-of-the-art reactor, where copper powder with a density ps = 8900 kg / m3 is used in the reactor at the start of the process; Α2 = a state-of-the-art reactor, in which amalgam powder with a density ps = 4450 kg / m3 is formed as a continuation of cementation reactions;

B1 = a reactor according to the invention wherein copper powder with a density ps = 8900 kg / m3 is used in the reactor at the start of the process;

B2 = a reactor according to the invention, wherein copper powder with a density ps = 4450 kg / m3 is formed as a continuation of the cementing reactions of the process.

Table 1 - Reactor Dimensions and Processing Conditions, and Situation at Process Start

Reactor Lower Section Diameter Lower mm 150 Upper Section Diameter Upper Ts mm 345 Lower Section Effective Height Zinfer mm 530 Upper Section Effective Height Zsuper mm mm 600 Solution Quantity Q Flow m3 / h 1.3 Density Pl kg / m3 1230 Viscosity ηι mPas 1.9 Drain Speed at Wesemp.lower m / s 0,020 Bottom Section Drainage Speed at Wesemp.more m / s 0.0039 Top Section Pulverized Solid Copper Amalgam Initial charge (coarse + M0 + mQ Kg 24, 8 25, 0 fine) Early fine portion M0 / M0 + m0)% 33,6 67,3 Density Ps kg / m3 8900 4450 Dlim limit size μχη 96,4 148,7 particle (Wdecant = Wsoi) Emptying (sun / bed ε 0, 67 0, 74 integer Table 2 - Dust Separation Analysis (identical for grate separation of dust)

Screen Size Pass through the Screen mesh mm% 30,595 100 40 0,420 99.4 50 0 297 96.5 70 0.210 87, 2 100 0, 149 67.5 140 0, 105 40, 0 200 0 .074 17, 3 270 0, 053 5.5 325 0, 044 2.5 400 0, 037 1.1 5 Table 3 - Situation at the End of Processing

Case Al A2 Bl B2 Final Lot (coarse + Mt + mt kg 16.3 8 24 20.8 thin) "Fines" removed from mt kg 8, 5 17 0.8 4 reactor "Fines" removed from mt / M0 + mo )% 34 68 3 16 final This is a case of a cementation reactor where copper powder is used as the initial charge in the fluidized bed.

The circulating solution reacts with copper, after which amalgam particles are formed in the cementation reaction and at some stage they are almost the original size of the copper particles with respect to the grain size, but considerably more. porous. Thus their density decreases and at the same time the number of particles having the same settling rate as the solution flow rate increases. The limiting particle size (dum) was calculated in the Table, of which the clarification rate is the same as the solution flow rate, as the solution rises from the fluidized bed towards the clarification zone.

It has been found that the arrangement according to the present invention has enabled a significant reduction in the amount of dust removed from the reactor.

- with copper powder: invention / state of the art = Bi / Al = 3 / 34.0 = 0.09, ie approximately 1/10;

with amalgam: invention / state of the art = B2 / A2 = 16/68 = 0.24, ie approximately 1/4.

As shown in the Example, when using a reactor construction according to the present invention, the amount of dust removed from the reactor with the solution dropped to one tenth and even a more difficult case to a quarter.

Example 2

In the device according to Figure 4, silver

was removed from a cuprous chloride solution using a fluidized copper powder bed. The diameter of the reactor reaction zone in which the fluidized bed was formed was 1.5 m and the height 3.5 m. The lower part of the reaction zone 10 was equipped with a four-blade agglomerate mixer, which had a blade pitch type and a diameter of 0.6 m.

The diameter of the clarification zone was 3.4 m and the height 4.5 m. A flow prevention plate was fixed around the discharge unit located in the clarification zone, in which case the plate was funnel type and had an outside diameter of 1.8 m. In addition, the discharge flow of the solution was directed by means of a guide ring which was fixed to extend internally from the clarification zone wall from a distance of 0.45 m. The guide ring was located above the flow prevention plate and at a distance of

0.4 m from the outer ring of said flow prevention plate.

The specific weight of the concentrated cuprous chloride solution was 1240 kg / m3, the pH 2.9 and the temperature 70 ° C. The solution was fed into the reaction zone of the mixing reactor at a flow rate of 130 m3 / h. The feed solution contained 145 mg / L silver, intended to cement it onto the surface of the copper powder. The copper powder used was 85% below 110 micrometers in size. It was estimated that a fluidization level was reached in the test, which was adjusted to correspond to a ε value of 0.7-0.8. The test showed that after 15 minutes the silver content of the cuprous chloride solution removed from the reactor was below the order of 10 mg / L, this remaining for a test period of approximately twenty four hours. The solids content of the solution to be removed from the reactor ranged from 0.5 to 3.0 g / L, which can be considered as an acceptable range.

Claims (20)

1. Mixing reactor (12), for mixing a liquid and a solid in a fluidized bed, for clarifying the solution that is formed and discharging the clarified solution from the reactor, wherein the reactor is composed of three zones, the lower zone of which it is essentially a cylindrical reaction zone (14) for forming the fluidized bed, whereby fixed to the upper part of the reaction zone is provided a resting zone (18), which conically extends upwardly, and connected The upper part of the latter has a cylindrical clarification zone (22), the diameter of which is the same as the upper section of the rest zone, characterized in that the lower section of the reaction zone (14) is provided with a connection of solution feed (13) and the clarifying zone (22) has a solution discharge unit (23, 32) located below the liquid surface (E), whose discharge opening (24, 33) is essentially disposed in the axis central reactor (D), and wherein at least one guide element (25, 26, 27, 34) for directing the solution flow is located in the vicinity of the discharge opening. Mixing reactor (12) according to Claim 1, characterized in that the supply connection (13) for feeding liquid into the reactor is directed obliquely downwards. Mixing reactor (12) according to Claim 1, characterized in that the clarified solution discharge unit (23) is directed obliquely downwardly and the guide element directing the solution flow is a slurry plate. annular flow prevention (25, 27), which is located around the discharge opening (24). Mixing reactor according to claim 3, characterized in that the flow prevention plate (25) is flat. Mixing reactor (12) according to Claim 3, characterized in that the flow prevention plate (27) is upwardly conical. Mixing reactor (12) according to claim 3, characterized in that the outside diameter of the flow prevention plate (25, 27) is 20-30% larger than the diameter T1 of the flow zone. reaction (14). Mixing reactor (12) according to Claim 1, characterized in that the clarified solution discharge unit (23) is directed obliquely downwards and that the guide elements which direct the solution flow are constituted of an annular flow prevention plate (25, 27) which is situated around the discharge opening (24) and a guide ring (26) above it directed from the reactor wall to the center of the reactor. Mixing reactor (12) according to Claim 7, characterized in that the guide ring (26) extends into the reactor wall at a distance of the order of 10-30% of the diameter. T3 of the clarification zone (22). Mixing reactor (12) according to Claim 1, characterized in that the clarified solution discharge unit (32) is directed upwardly and the guide element directing the solution flow is an adjustment shim. (34) which is below the discharge opening (33). Mixing reactor (12) according to Claim 1, characterized in that a choke ring (28) is placed between the reaction zone (14) and the rest zone (18) which is driven internally from the reactor wall. Mixing reactor (12) according to Claim 10, characterized in that there is a spacing (29) between the reactor wall and the choke ring. Mixing reactor (12) according to Claim 1, characterized in that the reaction zone (14) is provided with a rotor mixer (30) made of spiral tubes. 13 A method for mixing a liquid and a pulverulent solid together for clarifying the solution that is formed and removing the clarified solution from a mixing reactor, wherein a fluidized bed is disposed in the reaction zone (I) of the lower reactor section, said bed being formed of a liquid and solid, with a resting zone (II) above it, with an upward widening cross section and a clarifying zone (III) above it, which has the same section area upper section of the rest zone (II), characterized in that the liquid to be treated is fed into the lower section of the reaction zone, the cross-sectional area of the solution stream rising into the clarification zone ( III) is required to expand by at least one guide element (A) before the solution is discharged mainly through the discharge unit (B) located on the central axis (D) of the reactor; go The solution is forced to shrink by expanding its cross-sectional area and, at the same time, the flow is bound to form return swirls in the vicinity of the reactor wall, within which solid particles have moved together. with the solution decant and fall back into the fluidized bed. Method according to Claim 13, characterized in that the liquid to be treated is fed into the lower section of the reaction zone in an obliquely downward direction. Method according to Claim 13, characterized in that the upwardly extending solution flow cross-sectional area is required to expand by means of an essentially horizontal plate-like guide element located below the unit. discharge Method according to claim 13, characterized in that the upwardly extending solution flow cross-sectional area is required to expand by means of an annular guide element located around the discharge unit. Method according to claims 13 and 16, characterized in that the upwardly extending cross-sectional area of the solution flow is required to expand by annular guide elements located around and above the unit. discharge Method according to Claim 17, characterized in that the upwardly extending solution flow cross-sectional area is required to expand by annular guide elements located around and above the discharge unit. wherein the guide element above extends into the reactor wall at a distance of the order of 10-30% of the diameter of the clarification zone T3. Method according to claim 13, characterized in that the upwardly flowing solution of the solution from the fluidized bed of the reaction zone (I) within the resting zone (II) is stabilized by means of choke. Method according to claim 13, characterized in that the fluidized bed of the reaction zone (I) is mixed to stabilize the flow of the solution.